The present invention relates to an aerator.
More specifically, the invention is intended for an aerator that blows air into a distribution system placed under water in order to introduce air into the water.
Such an aerator is primarily used for the aeration of wastewater, so that decomposition processes of impurities work efficiently, but other applications, such as aerating other volumes of water, for example fish farm ponds or swimming pools, are also possible.
Traditionally wastewater basins are aerated by means of a compressor which, by means of a pipe network with valves, provides air to one or more air distribution systems equipped with diffusers placed on or close to the bottom of the basins.
These diffusers are designed to make very small air bubbles, whereby these devices have a very high aeration efficiency.
This efficiency is also known as the Standard Aeration Efficiency (SAE). This is the ratio between the quantity of oxygen introduced in the water and the required quantity of energy to introduce this oxygen in the water.
A disadvantage of such an aerator is that the compressor makes noise and must be cooled. Arrangements must be made for this.
An extensive pipe network, with many couplings, branches and valves, and consequently a high pressure drop, has to be constructed and maintained, because different places in basins have different aeration requirements, and aeration only has to be done if there is a need for it in order to prevent inefficiencies.
Furthermore there is a disadvantage that it is not easy to maintain and/or clean the air distribution systems, and thus to prevent blockages, because the basins have to be emptied for this purpose.
Also the mixing of the water in a basin is generally insufficient for optimum operation, such that additional means have to be used to obtain mixing.
Such aerators also have the disadvantage that they are expensive and cannot easily be moved and thus cannot be deployed flexibly, for example in cases where a fixed installation is too expensive, or is only needed now and again.
A number of these disadvantages are prevented by traditional systems that consist of a pump placed under water that pumps wastewater on its pumping side through a narrowing, and due to the underpressure thus occurring sucks in air via an intake pipe extending from the narrowings to above the water surface. The air sucked in is then pumped together with the pumped water under the water surface from the narrowing, such that the water in the basin is aerated.
However, such installations have a very low SAE, on the one hand because they have to pump large quantities of water for relatively small quantities of air, and on the other hand because they form relatively large air bubbles.
EP 0 163 821 relates to a device that is provided with a structure that can be placed in a basin as a whole. This device comprises a compressor that is placed below the water surface. It is clear that such a device is heavy and bulky, which makes it difficult to handle or move.
GB 1 268 426 concerns a device for aerating a liquid, and this device is equipped with a blower that rests on the bottom of a watercourse, and this blower is driven by an electric motor equipped with ball bearings. A problem with such a device is that it has to be pulled on to the bank for maintenance of the bearings and that it requires the presence of an oil lubricating circuit, which makes the device heavier to lift.